Enhanced gas-sensing performance of SnO2/Nb2O5 hybrid nanowires

Semiconductor tin oxide (SnO2) is acknowledged to be one of the semiconductor oxides with most potential for utilization as nitrogen dioxide (NO2)-sensor materials. However, the challenge to improve the gas sensitivity still remains, and this limits the full realization of the SnO2 sensor potential. In this paper, enhanced gas sensitivity obtained by the formation of a SnO2/niobium pentoxide (Nb2O5) hybrid structure is reported. As the NO2 concentration is lower to 3 ppm, the measured resistance in the SnO2/Nb2O5-based sensor is still 2.5 times larger than that in a pristine SnO2-based sensor. With an increase in the NO2 concentration, the response time of the SnO2/Nb2O5-based sensor decreases sharply whereas the pristine SnO2-based sensor response time increases. The enhanced performance is attributed to the presence of more oxygen vacancies and a higher specific surface area in the hybrid structure induced by the introduction of Nb2O5. These results provide some general guidelines for the selection of compositions to enhance the sensor performance.